The present invention relates to a flash memory device and more particularly to a method of reducing the size of a fuse circuit used in providing option information during power up of a flash memory device.
Recently, efforts for enhancing mobile devices such as a camcorder, a digital camera, a portable phone, an MP3 (MPEG-1 Layer3) player, etc has been performed accordingly as the demand for the mobile devices increases.
A NAND flash memory device employed in the mobile device operates in accordance with an application program, wherein initialization of the NAND flash memory device is determined in accordance with the operation characteristic of the mobile device.
Generally, a fuse circuit for storing option information in the flash memory device is made up of poly or metal, etc, and stores the option information through an electrical cutting method.
The fuse circuit is also employed in a repair circuit for repair operation in a flash memory device.
FIG. 1 is a view illustrating a repair address circuit in a common flash memory device.
In FIG. 1, the repair address circuit stores repair address information A<1:4> of 4 bits, and includes a P-MOS transistor P, a first to ninth N-MOS transistors N1 to N9, and a first to eighth fuses F1 to F8. Here, the repair address information is stored in the repair address circuit by cutting the first fuse F1 to the eighth fuse F8.
In the case that input address A<1:4> is identical to the repair address stored in the repair address circuit, a current path is formed from the P-MOS transistor P to the ninth N-MOS transistor N9. As a result, the P-MOS transistor P is coupled to a ground through the current path, and so a repair signal is outputted.
As described above, the flash memory device has repair address circuits for storing the repair address information corresponding to the addresses. Accordingly, many fuses are needed in the repair address circuits.
The flash memory device uses not only the repair address circuit but also a lot of sub-fuse circuits for storing various option information so as to enhance yield of the flash memory device.
However, the sub-fuse circuits occupy much space compared to a transistor, thereby affecting the size of a memory chip. In addition, in the case that the sub-fuse circuit is cut, the sub-fuse circuit cannot be connected again. As a result, yield may be lowered due to a cutting error.